The present invention relates to vehicle service systems, and in particular to adaptors configured for securing optical targets or angle sensors to a surface of a large diameter vehicle wheel assembly, such as a heavy duty truck wheel assembly, during a vehicle wheel alignment measurement or inspection procedure.
A vehicle wheel alignment measurement or inspection system consists generally of a console having a computer or processing unit, a number of sensors for providing data to the computer or processing unit, one or more display devices such as a monitor, and one or more input devices such as a keyboard. The processing unit is configured with one or more software applications, at least one of which is adapted to facilitate the measurement or inspection of alignment angles associated with one or more vehicle wheel assemblies on a vehicle, each consisting of a rim and an associated tire. The processing unit is configured to utilize input data received either from angle sensors mounted to the vehicle wheel assemblies, or from imaging sensors acquiring images of optical targets secured to the vehicle wheel assemblies, or a combination thereof.
Unlike the wheel assemblies often found on passenger vehicles, wheel assemblies found on heavy duty trucks often incorporate rims which are adapted for reversible mounting in dually wheel assemblies. As seen in FIGS. 1A and 1B, these rims are designed with highly convex surfaces to facilitate attachment to a wheel hub assembly in either an inner or outer position of a dual wheel arrangement. Typically, the rims are mounted with the convex surfaces projecting outward on single-wheel or steerable axles, such as found at the front of the vehicles, while the rims are mounted in the reverse configuration in the outermost position on dual-wheel axles, such as found at the rear of the vehicles. A variety of different placement configurations about a vehicle are possible, depending upon the number and type of axles present.
Traditionally, angle sensors or optical targets are temporarily affixed to these vehicle wheel assemblies utilizing precision rim-clamping wheel adaptors such as shown in FIG. 1C and 1D. These adaptors are configured to clamp onto either a hub bore edge of the rim as seen in FIG. 1C, or to the outer rim edge as seen in FIG. 1D. Once secured, the adaptors position a mounting point for an angle sensor or an optical target in a position which is substantially coaxial with the wheel assembly axis of rotation. These traditional precision rim-clamping wheel adaptors typically include a set of claws or feet adapted to secure the wheel adaptor to the wheel assembly by engaging an edge of the wheel rim, such as adjacent to the tire junction or the wheel hub. An adjustable centering mechanism on the wheel adaptor ensures that the claws or feet of the wheel adaptor are adjusted in a symmetrical manner to maintain the mounting point for the angle sensor or optical target in a determined configuration relative to the axial center of the rim surface being engaged.
To provide increased stability during rolling movement of the wheel assembly, some traditional precision wheel adaptors include clamps for gripping a circumferential tread surface of the associated tire, such as seen in U.S. Pat. No. 5,987,761 to Ohnesorge and U.S. Pat. No. 6,131,293 to Maioli et al. These traditional precision rim-clamping adaptors each utilize a set of gripping arms adapted to engage tire surfaces in conjunction with the set of contact supports and centering mechanisms for symmetrically engaging the circumferential lips of the wheel rims, and for securing the wheel adaptors in axially centered positions relative to the vehicle wheel assemblies onto which they are mounted.
When configured for use with large diameter highly convex (or concave) vehicle wheel assemblies, such as found on heavy duty trucks or vehicles with dually rear axles, traditional precision rim-clamping adaptors must be provided with enough structure to provide suitable clearances around the raised wheel assembly hub structures. As a result, traditional precision adapters often become large, heavy, and awkward to use with heavy duty vehicles. Furthermore, due to higher inflation pressures often used in the large diameter wheel assemblies of heavy duty vehicles, engagement of the claws or feet of a traditional precision adaptor into the interface between the tire and wheel rim edge of the wheel assembly become significantly more difficult. Overall, the process of attaching a traditional precision adaptor to a large diameter wheel on a heavy-duty vehicle with either a raised or recessed central hub surface is time consuming and prone to errors resulting from poor surface engagements.
Light-weight adaptor assemblies with optical targets have been developed for use when acquiring measurements from the wheel assemblies on passenger car and light truck wheels. These light-weight adaptor assemblies, such as shown in U.S. Pat. No. 8,341,848 B2 to Stieff et al. are designed to be placed against an outboard surface of a relatively flat-faced wheel rim, in a non-determined position over the wheel axis of rotation. A pair of wheel clamp arms are then engaged with the tread surfaces of the tire to retain the adaptor in place while measurements are acquired from a multi-surface optical target disposed on the outboard end of the adaptor. In order to minimize the weight and clamping force required to keep the adaptor secured to the vehicle wheel assembly during use, the structure of the adaptor is designed to carry the optical target as close to the vehicle wheel assembly outboard surface as possible. This structural design renders it difficult or impossible to utilize the light-weight passenger vehicle adaptor assemblies on a vehicle wheel assembly having a prominently raised central hub surface as seen in FIG. 1A without the use of extension components to provide the required clearance. Similarly, the light weight passenger vehicle adaptor assembly is difficult to utilize on a vehicle wheel assembly having a deeply recessed central hub surface as seen in FIG. 1B, due to a lack of planar surfaces onto which the adaptor base can be positioned in a stable manner.
Accordingly, it would be advantageous to provide a light-weight adaptor assembly suitable for use with either optical targets or angle sensors, and which can be secured to large diameter vehicle wheels on a heavy duty vehicle having prominently raised central hub surfaces easily and without concern for precise axial alignment or centering.
It would be further advantageous to provide a light-weight adaptor assembly suitable for use with either optical targets or angle sensors, and which can be secured to large diameter vehicle wheels on a heavy duty vehicle having deeply recessed central hub surfaces easily and without concern for precise axial alignment or centering.